As one of internal degrees of freedom of a stationary microscopic particle, there is a spin angular momentum. Nuclei of many atoms each also have this spin angular momentum. In thermal equilibrium, unless the temperature is as very low as less than 50 mK, the spin angular momenta of the atomic nuclei are normally in an unpolarized state of being directed in all directions with equal probability.
Since many atomic nuclei have fixed-magnitude nuclear spins, if the nuclear spins can be polarized, it is possible to obtain more detailed information about the dynamics.
Accordingly, for example, it is desirable to increase the degree of nuclear-spin polarization (the degree of alignment of nuclear spins) in the field of nuclear physics or the like.
On the other hand, since nuclear magnetic resonance (NMR) which is used in a variety of fields as a nondestructive and accurate analysis technique is low in sensitivity as compared with other analysis methods, it is desirable that its sensitivity be enhanced.
The signal intensity of NMR depends on the degree of nuclear-spin polarization and thus it is desirable to increase the degree of nuclear-spin polarization.
Further, a spin FET (Field Effect Transistor) and a quantum computer are proposed as the application of nuclear spins and, accordingly, it is becoming important to control nuclear spins.
As a nuclear-spin control method, there is a method using the so-called quantum Hall effect.
For example, Non-Patent Document 1 discloses a method that applies a magnetic field perpendicular to the two-dimensional surface of a GaAs-based two-dimensional quantum well and detects nuclear-spin polarization based on properties of the fractional quantum Hall effect or properties of the integer quantum Hall effect which occurs at that time (Non-Patent Document 1).
As another nuclear-spin control method, there is a method using circularly polarized light.
For example, Non-Patent Document 2 and Non-Patent Document 3 each disclose a technique that uses circularly polarized light for nuclear-spin control of a GaAs two-dimensional system (Non-Patent Document 2, Non-Patent Document 3).